This invention is concerned with writing instruments, and in particular relates to a reservoir pen in which a valve is provided to control flow of ink from an ink channel to the underside of a nib, the valve being opened in response to nib movements when the pen is in use.
A pen of the above kind is described in our European Patent No. EP 0472660 and has a valve member which extends through a hole in the nib and which is biased into sealing contact with the valve seat by a leaf spring positioned above the nib. In use, when the nib flexes upwardly, the valve member is lifted away from the seat, against the bias of the spring, by the nib. The need to provide the hole in the nib is an inconvenience from a manufacturing viewpoint, and the nib performance can be impaired by the nib being responsible for the valve opening.
The present invention addresses the shortcomings of the known construction and as an alternative it provides a reservoir pen comprising a valve for controlling flow of ink from an ink channel to the underside of a nib, the valve including a seat and a valve member springingly biased away from the seat for opening the valve and arranged to be urged by the nib against the spring bias and into sealing contact with the seat.
With this construction the nib does not require a hole to accommodate the valve member and its flexing characteristics are not influenced by having to lift the valve member off of the seat.
The spring bias may be exerted by a separate spring element, such as a leaf spring, by the valve member which for this purpose can be provided with a resilient portion, conveniently formed as an annular flange, or by a deformable valve seat member which is deformed by the valve member from a position in which they are not sealingly engaged to a position in which sealing engagement is established.